Abstract

No conclusive evidence that the direction in which photo-electrons are
ejected by X-rays depends in any way upon the nature of the atom from
which the ejection takes place has as yet been brought forward. Auger,
using the C. T. R. Wilson cloud expansion-chamber method, showed that
the most probable direction of ejection in a gas is a function of the frequency
of the incident X-rays, but the variations which he found in this
most probable direction with the nature of the gas used (oxygen or nitrogen,
argon, krypton, xenon) were probably less than the experimental error,
particularly as heterogeneous X-rays were used and the frequency of the
X-rays which were most effective in ejecting electrons may have varied
from gas to gas. Loughridge concluded that the most probable direction of
ejection was the same for water-vapor, air and argon, but the absorption energies of even the K-shells of all these atoms is so small that at best only
a small effect would be expected in these cases. Bothe using the point-discharge
ion-counter made observations on air and on gases the molecules
of which contained I, Br and Cl atoms. His results show small variations
with the nature of the gas, but again as heterogeneous X-rays were used
and his maxima were not sharp the variations were probably less than the
experimental accuracy.